A typical AC surface discharge type panel used as a plasma display panel (hereinafter referred to as “panel”) has many discharge cells between a front plate and a back plate that are faced to each other.
The front plate has the following elements:                a plurality of display electrode pairs disposed in parallel on a front substrate; and        a dielectric layer and a protective layer for covering the display electrode pairs.Here, each display electrode pair is formed of a pair of scan electrode and sustain electrode. The back plate has the following elements:        a plurality of data electrodes disposed in parallel on a back substrate;        a dielectric layer for covering the data electrodes;        a plurality of barrier ribs disposed on the dielectric layer in parallel with the data electrodes; andphosphor layers disposed on the surface of the dielectric layer and on side surfaces of the barrier ribs.        
The front plate and back plate are faced to each other so that the display electrode pairs and the data electrodes three-dimensionally intersect, and are sealed. Discharge gas containing xenon at a partial pressure of 5%, for example, is filled into a discharge space. Discharge cells are disposed in intersecting parts of the display electrode pairs and the data electrodes. In the panel having this structure, ultraviolet rays are emitted by gas discharge in each discharge cell. The ultraviolet rays excite respective phosphors of red, green, and blue to emit light, and thus provide color display.
A subfield method is generally used as a method of driving the panel. In this method, one field period is divided into a plurality of subfields, and the subfields at which light is emitted are combined, thereby performing gradation display.
Each subfield has an initializing period, an address period, and a sustain period. In the initializing period, initializing discharge is performed to form a wall charge required for a subsequent addressing operation on each electrode. The initializing operation includes an initializing operation (hereinafter referred to as “all-cell initializing operation”) of causing initializing discharge in all discharge cells, and an initializing operation (hereinafter referred to as “selective initializing operation”) of selectively causing initializing discharge in a discharge cell having performed sustain discharge in the sustain period of the last subfield.
In the address period, address discharge is selectively performed to form a wall charge in a discharge cell where display is to be performed. In the sustain period, sustain pulses are alternately applied to the display electrode pairs formed of the scan electrodes and the sustain electrodes, sustain discharge is caused in the discharge cell having performed address discharge, and a phosphor layer of the corresponding discharge cell is light-emitted, thereby displaying an image.
Of the subfield method, a panel driving method is proposed. In this driving method, the contrast can be kept sharp by reducing the background luminance, and the dynamic false contour can be reduced by suppressing the variation in brightness of picture. This method is disclosed in patent document 1, for example.
Of the subfield method, a new driving method is disclosed. In this driving method, the initializing discharge is performed using a gently varying ramp waveform voltage, and the initializing discharge is selectively applied to the discharge cell having performed sustain discharge. Thus, light emission that is not related to the gradation display is minimized, and the contrast ratio is improved.
Specifically, in the initializing period of one of a plurality of subfields, the all-cell initializing operation of causing discharge from all discharge cells is performed. In the initializing period of another subfield, the selective initializing operation of initializing only the discharge cell having performed sustain discharge in the sustain period of the last subfield is performed. As a result, light emission that is not related to the display is only the light emission accompanying the discharge of the all-cell initializing operation, and an image having high contrast can be displayed. This driving method is disclosed in patent document 2, for example.
In a panel where the partial pressure of xenon is increased to improve the light emitting efficiency, the initializing discharge becomes unstable, and a address failure can occur in the subsequent address period. A driving method of the panel where high-quality image is displayed by stabilizing the initializing discharge is proposed. The driving method is disclosed in patent document 3, for example.
Recently, while the improvement of image display quality has been demanded, factors destabilizing the discharge have been increased by enlargement of the panel, refining of the discharge cell, or increase in the xenon partial pressure. If the above-mentioned all-cell initializing operation becomes unstable dependently on the display image and a malfunction (hereinafter referred to as “false lighting”) for causing sustain discharge in the discharge cell that has not caused address discharge occurs, the image display quality can be reduced significantly.
[Patent document 1] Japanese Patent Unexamined Publication No. 2001-255847
[Patent document 2] Japanese Patent Unexamined Publication No. 2000-242224
[Patent document 3] Japanese Patent Unexamined Publication No. 2005-326612